The present invention relates to electrical connectors; and more particularly, it relates to electrical connectors of the type which are referred to generally as xe2x80x9cquick disconnectxe2x80x9d connectors and which are used in commercial and industrial applications, particularly in the field of industrial automation and manufacturing.
Typically, quick disconnect connectors for commercial and industrial applications of the type with which the present invention is concerned, include a male connector and a mating female connector. The male connector has metal connecting elements in the form of pins; and they are received in corresponding sockets or receptacles embedded in the mating female connector. Typically, these connectors have two to five poles plus a ground connection.
An important aspect of quick disconnect connectors is that there be some mechanical coupling to secure the male and female connectors together and maintain electrical continuity. Typically, in connectors of this type, the female connector (or the male) is provided with a mating threaded coupling member (such as a coupling nut); and the mating connector is provided with a mating threaded coupling portion so that after the electrical connection is established, the coupling members provide a mechanical connection securing the electrical connection. In some applications where the handling of the connectors may be often and perhaps somewhat rough, as well as in applications where the connectors are mounted to a machine and undergo periodic or continuous vibration, there is a tendency for the coupling nut to back off from its threaded engagement with the male connector, thus creating the possibility of an inadvertent or unintentional disconnect.
In addition to the problems mentioned above concerning the possibility that the male and female connectors may become disconnected as a result of vibration or handling, there is also a disadvantage with existing quick disconnect connectors in that it takes an appreciable time to secure a connection, primarily in manually threading the coupling nut of one connector onto the other connector. The amount of time for assembling a single connector combination may not be significant in an absolute sense, but when it is considered that in a large manufacturing environment there are literally thousands of such connectors around and that machines and control systems employing the connectors are continuously being re-positioned, tested and re-assembled, over the period of months or a year, the amount of time required to assemble and disassemble threaded coupling nuts has proved to be appreciable.
Co-owned, copending U.S. application Ser. No. 09/945,970, filed Sep. 4, 2001, discloses a vibration resistant, quick disconnect connector having thread segments of flexible material which permits male and female connectors to be assembled simply by pushing them together. The female connector has the flexible thread segments on a flexible wall which deflects to permit mating engagement when pushed onto a male connector.
Such flexible-thread connectors work very well when assembled to a corresponding mating conventional connector having threads of matching pitch.
Typically, such conventional connectors have threads of metal or rigid plastic; and the inter-engagement of flexible thread segments with full mating threads of rigid material has been found to be satisfactory because the act of connecting the two is simplified, and the resistance to vibration-induced disconnect is acceptable. However, in the case of female to male inter-engagement with mating connectors both having flexible threads the connection leaves something to be desired for two reasons. First, there is little or no tactile feeling that the connection has been completed; second, because the crests of flexible threads may be somewhat lower than for rigid threads, the ability to resist vibration-induced disconnect is less than desired.
The present invention contemplates that one of the electrical connectors (the female in the embodiment shown) have a cylindrical wall surrounding and spaced from an insulating insert in which connecting elements in the form of sockets are embedded. The cylindrical wall of the female connector is made of molded plastic, such as polyvinyl chloride (PVC) and has a flexibility such that it may be deformed upon insertion of a mating male connector in order to receive and engage with the mating thread segments of the male connector without a turning or twisting motion. The interior surface of the cylindrical wall of the female connector is provided with first and second diametrically located, discrete segments of internal threads arranged in opposing relation. That is, one segment of internal threads may extend for approximately 90 degrees about the interior of the cylindrical wall; and a second segment of internal threads is arranged in opposing or facing relation and located on the interior surface of the opposite side of the peripheral wall. Between the two segments of thread, the wall is free of thread and may be smooth and cylindrical.
When used in connection with the present invention, the term xe2x80x9cthreadxe2x80x9d includes not only conventional screw threads, extending helically about a central axis, but also a series of alternating ridges or crests and troughs arranged perpendicular to the longitudinal axis of the connector (sometimes referred to as xe2x80x9cparallelxe2x80x9d threads). Conventional screw threads may be preferred because they are compatible with the screw threads found on the many existing metal or rigid plastic coupling nuts and male connectors found in manufacturing plants. However, parallel threads, when provided in discrete segments as disclosed, will engage and can be assembled by pushing two mating connectors together because the threads are flexible and they are provided in discrete segments so they will ride over one another upon assembly. Parallel threads will provide sufficient interlocking to require separating or pull forces in a desirable range to resist unintentional disconnects. Moreover, a xe2x80x9cthreadxe2x80x9d includes at least two adjacent crest/trough combinations, whether parallel or helical.
The male connector preferably has corresponding, matching opposing segments of external thread on an outer cylindrical surface. The male and female connector inserts are keyed together so that when the keyway of the female is aligned with the key of the male connector, the matching thread segments are also aligned.
The male connector may then be inserted into the female connector by pushing the male connector directly into the female connector after the respective key and keyway have been aligned. In assembling the male connector to the female connector, the wall of the female connector deflects as the external thread segments of the male connector are assembled to the mating thread segments female connector. In other words, the outer wall of the female connector deforms into an elliptical form so that the interior threads of the female connector ride over the corresponding thread segments of the male connector.
Once the two connectors are assembled, the threads inter-engage (whether parallel or helical types). The connection is highly resistant to vibration-induced disconnect because the male connector cannot be rotated relative to the female connector since they are keyed together. Moreover, it has been found that a substantial but adjustable pull force (in the range of ten to thirty pounds, for example) may be designed into the assembled connectors, depending upon the hardness of the material used in molding the cylindrical wall of the female connector on which the thread segments are formed and other factors.
It will be appreciated that the assembly time for establishing an electrical/mechanical connection with the improved connectors is substantially reduced. Moreover, the female connector of the present invention (with screw threads) is adaptable to mate with existing male connectors having external metal or other rigid threads, and the male version of the instant connector with flexible screw threads is equally adaptable to assembly with existing interior metal threads of rigid coupling nuts. The male connector of the present invention may be pushed directly into the existing coupling nuts of female connectors, or, if desired, the coupling nuts can be threaded onto the thread segments of the male connectors constructed according to the present invention.
In order to improve the coupling of a male and a female connector, each having flexible threads, the present invention provides an annular groove at the forward end of one set of thread segments, typically, but not necessarily, located on the female connector and located on the interior surface of the flexible wall. A mating annular rib or rim is provided at the base of the exterior thread of the male connector. When the two connectors are aligned and assembled with a linear, pushing motion, the thread segments ride over one another, the outer wall of the female connector flexing to receive the male; and, as the engagement becomes complete, the annular rim of the male connector snaps into engagement with the annular groove of the female. This provides both a sensible, tactile feel of completion of the connection, and a solid mechanical coupling to resist disconnect of the mating flexible threads.
Further, the outer surfaces of the overmold bodies, for both male and female are shaped and textured to facilitate gripping and disconnecting with the fingers of both hands.
Other features and advantages of the present invention will be apparently to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.